Form Calculation

I've created a form where the form field integer values are added to create and display a total once submitted, but my form is displaying a Mismatch error. Do anyone have any suggestions?

<% dim field1, field2, field3
field1 = request.form("field1")
field2 = request.form("field2")
field3 = request.form("field3")
total = field1*1 + field2*1 + field3*1
%>

<form action="untitled2.asp" method="post">
Field 1:&nbsp;&nbsp;<input type="text" name="field1"><BR><BR>
Field 2:&nbsp;&nbsp;<input type="text" name="field2"><BR><BR>
Field 3:&nbsp;&nbsp;<input type="text" name="field3"><BR><BR>
<input type="Submit" value="Submit">
<br><BR><BR>
<%=total%>
</form>